net/ipv4/udp_offload.c

   1 /*
   2  *      IPV4 GSO/GRO offload support
   3  *      Linux INET implementation
   4  *
   5  *      This program is free software; you can redistribute it and/or
   6  *      modify it under the terms of the GNU General Public License
   7  *      as published by the Free Software Foundation; either version
   8  *      2 of the License, or (at your option) any later version.
   9  *
  10  *      UDPv4 GSO support
  11  */
  12
  13 #include <linux/skbuff.h>
  14 #include <net/udp.h>
  15 #include <net/protocol.h>
  16
  17 static DEFINE_SPINLOCK(udp_offload_lock);
  18 static struct udp_offload_priv __rcu *udp_offload_base __read_mostly;
  19
  20 #define udp_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&udp_offload_lock))
  21
  22 struct udp_offload_priv {
  23         struct udp_offload      *offload;
  24         struct rcu_head         rcu;
  25         struct udp_offload_priv __rcu *next;
  26 };
  27
  28 static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
  29         netdev_features_t features,
  30         struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
  31                                              netdev_features_t features),
  32         __be16 new_protocol, bool is_ipv6)
  33 {
  34         struct sk_buff *segs = ERR_PTR(-EINVAL);
  35         u16 mac_offset = skb->mac_header;
  36         int mac_len = skb->mac_len;
  37         int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
  38         __be16 protocol = skb->protocol;
  39         netdev_features_t enc_features;
  40         int udp_offset, outer_hlen;
  41         unsigned int oldlen;
  42         bool need_csum = !!(skb_shinfo(skb)->gso_type &
  43                             SKB_GSO_UDP_TUNNEL_CSUM);
  44         bool remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
  45         bool offload_csum = false, dont_encap = (need_csum || remcsum);
  46
  47         oldlen = (u16)~skb->len;
  48
  49         if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
  50                 goto out;
  51
  52         skb->encapsulation = 0;
  53         __skb_pull(skb, tnl_hlen);
  54         skb_reset_mac_header(skb);
  55         skb_set_network_header(skb, skb_inner_network_offset(skb));
  56         skb->mac_len = skb_inner_network_offset(skb);
  57         skb->protocol = new_protocol;
  58         skb->encap_hdr_csum = need_csum;
  59         skb->remcsum_offload = remcsum;
  60
  61         /* Try to offload checksum if possible */
  62         offload_csum = !!(need_csum &&
  63                           ((skb->dev->features & NETIF_F_HW_CSUM) ||
  64                            (skb->dev->features & (is_ipv6 ?
  65                             NETIF_F_IPV6_CSUM : NETIF_F_IP_CSUM))));
  66
  67         /* segment inner packet. */
  68         enc_features = skb->dev->hw_enc_features & features;
  69         segs = gso_inner_segment(skb, enc_features);
  70         if (IS_ERR_OR_NULL(segs)) {
  71                 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
  72                                      mac_len);
  73                 goto out;
  74         }
  75
  76         outer_hlen = skb_tnl_header_len(skb);
  77         udp_offset = outer_hlen - tnl_hlen;
  78         skb = segs;
  79         do {
  80                 struct udphdr *uh;
  81                 int len;
  82                 __be32 delta;
  83
  84                 if (dont_encap) {
  85                         skb->encapsulation = 0;
  86                         skb->ip_summed = CHECKSUM_NONE;
  87                 } else {
  88                         /* Only set up inner headers if we might be offloading
  89                          * inner checksum.
  90                          */
  91                         skb_reset_inner_headers(skb);
  92                         skb->encapsulation = 1;
  93                 }
  94
  95                 skb->mac_len = mac_len;
  96                 skb->protocol = protocol;
  97
  98                 skb_push(skb, outer_hlen);
  99                 skb_reset_mac_header(skb);
 100                 skb_set_network_header(skb, mac_len);
 101                 skb_set_transport_header(skb, udp_offset);
 102                 len = skb->len - udp_offset;
 103                 uh = udp_hdr(skb);
 104                 uh->len = htons(len);
 105
 106                 if (!need_csum)
 107                         continue;
 108
 109                 delta = htonl(oldlen + len);
 110
 111                 uh->check = ~csum_fold((__force __wsum)
 112                                        ((__force u32)uh->check +
 113                                         (__force u32)delta));
 114                 if (offload_csum) {
 115                         skb->ip_summed = CHECKSUM_PARTIAL;
 116                         skb->csum_start = skb_transport_header(skb) - skb->head;
 117                         skb->csum_offset = offsetof(struct udphdr, check);
 118                 } else if (remcsum) {
 119                         /* Need to calculate checksum from scratch,
 120                          * inner checksums are never when doing
 121                          * remote_checksum_offload.
 122                          */
 123
 124                         skb->csum = skb_checksum(skb, udp_offset,
 125                                                  skb->len - udp_offset,
 126                                                  0);
 127                         uh->check = csum_fold(skb->csum);
 128                         if (uh->check == 0)
 129                                 uh->check = CSUM_MANGLED_0;
 130                 } else {
 131                         uh->check = gso_make_checksum(skb, ~uh->check);
 132
 133                         if (uh->check == 0)
 134                                 uh->check = CSUM_MANGLED_0;
 135                 }
 136         } while ((skb = skb->next));
 137 out:
 138         return segs;
 139 }
 140
 141 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
 142                                        netdev_features_t features,
 143                                        bool is_ipv6)
 144 {
 145         __be16 protocol = skb->protocol;
 146         const struct net_offload **offloads;
 147         const struct net_offload *ops;
 148         struct sk_buff *segs = ERR_PTR(-EINVAL);
 149         struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
 150                                              netdev_features_t features);
 151
 152         rcu_read_lock();
 153
 154         switch (skb->inner_protocol_type) {
 155         case ENCAP_TYPE_ETHER:
 156                 protocol = skb->inner_protocol;
 157                 gso_inner_segment = skb_mac_gso_segment;
 158                 break;
 159         case ENCAP_TYPE_IPPROTO:
 160                 offloads = is_ipv6 ? inet6_offloads : inet_offloads;
 161                 ops = rcu_dereference(offloads[skb->inner_ipproto]);
 162                 if (!ops || !ops->callbacks.gso_segment)
 163                         goto out_unlock;
 164                 gso_inner_segment = ops->callbacks.gso_segment;
 165                 break;
 166         default:
 167                 goto out_unlock;
 168         }
 169
 170         segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
 171                                         protocol, is_ipv6);
 172
 173 out_unlock:
 174         rcu_read_unlock();
 175
 176         return segs;
 177 }
 178
 179 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 180                                          netdev_features_t features)
 181 {
 182         struct sk_buff *segs = ERR_PTR(-EINVAL);
 183         unsigned int mss;
 184         __wsum csum;
 185         struct udphdr *uh;
 186         struct iphdr *iph;
 187
 188         if (skb->encapsulation &&
 189             (skb_shinfo(skb)->gso_type &
 190              (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
 191                 segs = skb_udp_tunnel_segment(skb, features, false);
 192                 goto out;
 193         }
 194
 195         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
 196                 goto out;
 197
 198         mss = skb_shinfo(skb)->gso_size;
 199         if (unlikely(skb->len <= mss))
 200                 goto out;
 201
 202         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
 203                 /* Packet is from an untrusted source, reset gso_segs. */
 204                 int type = skb_shinfo(skb)->gso_type;
 205
 206                 if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
 207                                       SKB_GSO_UDP_TUNNEL |
 208                                       SKB_GSO_UDP_TUNNEL_CSUM |
 209                                       SKB_GSO_TUNNEL_REMCSUM |
 210                                       SKB_GSO_IPIP |
 211                                       SKB_GSO_GRE | SKB_GSO_GRE_CSUM) ||
 212                              !(type & (SKB_GSO_UDP))))
 213                         goto out;
 214
 215                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
 216
 217                 segs = NULL;
 218                 goto out;
 219         }
 220
 221         /* Do software UFO. Complete and fill in the UDP checksum as
 222          * HW cannot do checksum of UDP packets sent as multiple
 223          * IP fragments.
 224          */
 225
 226         uh = udp_hdr(skb);
 227         iph = ip_hdr(skb);
 228
 229         uh->check = 0;
 230         csum = skb_checksum(skb, 0, skb->len, 0);
 231         uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
 232         if (uh->check == 0)
 233                 uh->check = CSUM_MANGLED_0;
 234
 235         skb->ip_summed = CHECKSUM_NONE;
 236
 237         /* Fragment the skb. IP headers of the fragments are updated in
 238          * inet_gso_segment()
 239          */
 240         segs = skb_segment(skb, features);
 241 out:
 242         return segs;
 243 }
 244
 245 int udp_add_offload(struct udp_offload *uo)
 246 {
 247         struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC);
 248
 249         if (!new_offload)
 250                 return -ENOMEM;
 251
 252         new_offload->offload = uo;
 253
 254         spin_lock(&udp_offload_lock);
 255         new_offload->next = udp_offload_base;
 256         rcu_assign_pointer(udp_offload_base, new_offload);
 257         spin_unlock(&udp_offload_lock);
 258
 259         return 0;
 260 }
 261 EXPORT_SYMBOL(udp_add_offload);
 262
 263 static void udp_offload_free_routine(struct rcu_head *head)
 264 {
 265         struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
 266         kfree(ou_priv);
 267 }
 268
 269 void udp_del_offload(struct udp_offload *uo)
 270 {
 271         struct udp_offload_priv __rcu **head = &udp_offload_base;
 272         struct udp_offload_priv *uo_priv;
 273
 274         spin_lock(&udp_offload_lock);
 275
 276         uo_priv = udp_deref_protected(*head);
 277         for (; uo_priv != NULL;
 278              uo_priv = udp_deref_protected(*head)) {
 279                 if (uo_priv->offload == uo) {
 280                         rcu_assign_pointer(*head,
 281                                            udp_deref_protected(uo_priv->next));
 282                         goto unlock;
 283                 }
 284                 head = &uo_priv->next;
 285         }
 286         pr_warn("udp_del_offload: didn't find offload for port %d\n", ntohs(uo->port));
 287 unlock:
 288         spin_unlock(&udp_offload_lock);
 289         if (uo_priv)
 290                 call_rcu(&uo_priv->rcu, udp_offload_free_routine);
 291 }
 292 EXPORT_SYMBOL(udp_del_offload);
 293
 294 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
 295                                  struct udphdr *uh)
 296 {
 297         struct udp_offload_priv *uo_priv;
 298         struct sk_buff *p, **pp = NULL;
 299         struct udphdr *uh2;
 300         unsigned int off = skb_gro_offset(skb);
 301         int flush = 1;
 302
 303         if (NAPI_GRO_CB(skb)->udp_mark ||
 304             (skb->ip_summed != CHECKSUM_PARTIAL &&
 305              NAPI_GRO_CB(skb)->csum_cnt == 0 &&
 306              !NAPI_GRO_CB(skb)->csum_valid))
 307                 goto out;
 308
 309         /* mark that this skb passed once through the udp gro layer */
 310         NAPI_GRO_CB(skb)->udp_mark = 1;
 311
 312         rcu_read_lock();
 313         uo_priv = rcu_dereference(udp_offload_base);
 314         for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
 315                 if (uo_priv->offload->port == uh->dest &&
 316                     uo_priv->offload->callbacks.gro_receive)
 317                         goto unflush;
 318         }
 319         goto out_unlock;
 320
 321 unflush:
 322         flush = 0;
 323
 324         for (p = *head; p; p = p->next) {
 325                 if (!NAPI_GRO_CB(p)->same_flow)
 326                         continue;
 327
 328                 uh2 = (struct udphdr   *)(p->data + off);
 329
 330                 /* Match ports and either checksums are either both zero
 331                  * or nonzero.
 332                  */
 333                 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
 334                     (!uh->check ^ !uh2->check)) {
 335                         NAPI_GRO_CB(p)->same_flow = 0;
 336                         continue;
 337                 }
 338         }
 339
 340         skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
 341         skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
 342         NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
 343         pp = uo_priv->offload->callbacks.gro_receive(head, skb,
 344                                                      uo_priv->offload);
 345
 346 out_unlock:
 347         rcu_read_unlock();
 348 out:
 349         NAPI_GRO_CB(skb)->flush |= flush;
 350         return pp;
 351 }
 352
 353 static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
 354                                          struct sk_buff *skb)
 355 {
 356         struct udphdr *uh = udp_gro_udphdr(skb);
 357
 358         if (unlikely(!uh))
 359                 goto flush;
 360
 361         /* Don't bother verifying checksum if we're going to flush anyway. */
 362         if (NAPI_GRO_CB(skb)->flush)
 363                 goto skip;
 364
 365         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
 366                                                  inet_gro_compute_pseudo))
 367                 goto flush;
 368         else if (uh->check)
 369                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
 370                                              inet_gro_compute_pseudo);
 371 skip:
 372         NAPI_GRO_CB(skb)->is_ipv6 = 0;
 373         return udp_gro_receive(head, skb, uh);
 374
 375 flush:
 376         NAPI_GRO_CB(skb)->flush = 1;
 377         return NULL;
 378 }
 379
 380 int udp_gro_complete(struct sk_buff *skb, int nhoff)
 381 {
 382         struct udp_offload_priv *uo_priv;
 383         __be16 newlen = htons(skb->len - nhoff);
 384         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 385         int err = -ENOSYS;
 386
 387         uh->len = newlen;
 388
 389         rcu_read_lock();
 390
 391         uo_priv = rcu_dereference(udp_offload_base);
 392         for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
 393                 if (uo_priv->offload->port == uh->dest &&
 394                     uo_priv->offload->callbacks.gro_complete)
 395                         break;
 396         }
 397
 398         if (uo_priv) {
 399                 NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
 400                 err = uo_priv->offload->callbacks.gro_complete(skb,
 401                                 nhoff + sizeof(struct udphdr),
 402                                 uo_priv->offload);
 403         }
 404
 405         rcu_read_unlock();
 406
 407         if (skb->remcsum_offload)
 408                 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
 409
 410         skb->encapsulation = 1;
 411         skb_set_inner_mac_header(skb, nhoff + sizeof(struct udphdr));
 412
 413         return err;
 414 }
 415
 416 static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
 417 {
 418         const struct iphdr *iph = ip_hdr(skb);
 419         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 420
 421         if (uh->check) {
 422                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
 423                 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
 424                                           iph->daddr, 0);
 425         } else {
 426                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
 427         }
 428
 429         return udp_gro_complete(skb, nhoff);
 430 }
 431
 432 static const struct net_offload udpv4_offload = {
 433         .callbacks = {
 434                 .gso_segment = udp4_ufo_fragment,
 435                 .gro_receive  = udp4_gro_receive,
 436                 .gro_complete = udp4_gro_complete,
 437         },
 438 };
 439
 440 int __init udpv4_offload_init(void)
 441 {
 442         return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
 443 }